EditorialCorrosion of Materials after Advanced Surface Processing,Joining, and Welding

Xizhang Chen ,1 Arvind Singh ,2 Sergey Konovalov ,3

Juergen R. Hirsch,4 and KaiWang 5

1College of Mechanical and Electrical Engineering, Wenzhou University, Wenzhou, China2Department of Mechanical Engineering, Kumaraguru College of Technology (KCT), Tamil Nadu, India3Department of Metals Technology and Aviation Materials, Samara National Research University, Samara, Russia4Hydro Aluminium Deutschland GmbH, Bonn, Germany5Department of Mechatronics Engineering, Foshan University, Foshan City, China

Correspondence should be addressed to Xizhang Chen; chenxizhang@wzu.edu.cn

Received 15 July 2018; Accepted 17 July 2018; Published 2 September 2018

Copyright © 2018 Xizhang Chen et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Corrosion has been a subject of keen scientific research forthe past 150 years. It has a great impact on the safety andreliability in wide range of applications and also on the econ-omy. Corrosion plays a crucial role in determining the life-cycle performance, safety, and cost of engineered products.Further, with the increasing demand for materials with mul-tiple performance capability, advanced surface processing,surface coatings, joining, and welding techniques are beingemployed. As these materials and methods will be utilizedin technologies for high-end applications (e.g., aerospace andnuclear engineering), investigation of corrosion of advancedsurfaced materials becomes essential.

Metal joining is a controlled process that is widelyemployed to fuse similar/dissimilar metals. Among the sev-eral metal joining techniques, welding is one of the mostwidely used for a variety of applications. Metallurgical,physical, and chemical changes caused by welding processesseverely affect the corrosion resistance of welds [1, 2]. Someof the recent and advanced welding processes include use ofelectron beam and laser beam for welding, and they havethe advantage of narrow heat affected zone [3]. Even withthe use of such advanced welding techniques, materials arestill prone to corrosion, invariably due to (i) variation incomposition, (ii) accumulation of residual stress, and (iii)modification inmicrostructure in theweld zone [1]. Similarly,solder joints undergo corrosion depending upon the localenvironmental conditions. Solder joints are severely prone

to galvanic corrosion as they are comprised of dissimilarmetals or alloy components that are in contact with eachother. In particular, the phenomenon of electromigration isprevalent in solder joints, wherein corrosion causes build-up of by-product material between the two metal structuresof different electrical potentials, resulting in a short-circuit[4].

Another major corrosion phenomenon which is accel-erated by the presence of stress is stress corrosion cracking(SCC). In SCC, the imposition of mechanical loads (inparticular tensile stress) on the structure causes increasedsensitivity to corrosion. The required tensile stress for SCCcrack growth may be in the form of directly applied stress(i.e., external stress) or in the form of residual stress (internal)[5]. SCC causes catastrophic failure in weldments. Recently,nanocrystalline (NC) materials (i.e., average grain sizes <100 nm) are under intense research for their surface proper-ties. In particular, nanocrystalline Ni-coatings are preferredas corrosion resistant coatings for metallic substrates [6].The small grain size and the high volume fraction of grainboundaries would result in corrosion behavior differentfrom that of polycrystalline materials. However, the effectof nanocrystallinity on the corrosion behavior is reportedto vary among metal systems and corrosion environments.This makes it difficult to predict the electrochemical behaviorof nanocrystalline coatings from that of their coarse-grainedcounterparts [7].

HindawiInternational Journal of CorrosionVolume 2018, Article ID 3569282, 3 pageshttps://doi.org/10.1155/2018/3569282

2 International Journal of Corrosion

While corrosion can act as a single most dominantform of degradation in metallic structures, in real-timeapplications, it is still a difficult problem to characterize,quantify, and eliminate. With advancement in analyticaltechniques and superior instrumentation, future researchworkwill providemore efficient solutions to control,monitor,and prevent corrosion.

This special issue encompasses recent research on corro-sion of materials after advanced surface processing, joining,and welding. It contains 6 original research articles address-ing various aspects related to welding, stress corrosion,soldering, and nanocrystalline coatings used in awide varietyof applications, summarized as follows.

1. Corrosion of Weldments

1.1. Research Article: “Corrosion Behavior of Welded Joint ofQ690 with CMT Twin”. In this research article, low-alloysteel of Q690 was welded with the method of CMT Twin.Cold metal transfer (CMT) process is a combination of 2independently functioning arc-welding processes into onesingle process. Q690 steel is low carbon bainitic steel usedin offshore industry. The exposure of the steel to salineenvironment usually leads to severe corrosion problems.In particular, the presence of Cl− ion from salts such asNaCl and MgCl

2in the chloride environment destroys the

protective film and increases the severity of corrosion. Inthis paper the corrosion behaviour of CMT weld joint in3.5% NaCl solution was reported. Hardness increase due tothe appearance of troostite has been observed. While thecorrosion products of regions with varying microstructureremained the same, at the welded joints Fe (OH)

2changed

to Fe (OH)3. Interestingly, the CMT weld zone showed

lower corrosion when compared to the overheated zone andthe base metal. The better corrosion behaviour at the weldzone was attributed to the presence of nickel. The degree ofcorrosion with respect to microstructure varied as follows:HAZ > BM >WZ.

1.2. Research Article: “Effect of Rare-Earth Elements on theCorrosion Resistance of Flux-Cored Arc-Welded Metal with10CrNi3MoVSteel”. In this researchwork, the flux-cored arc-welding (FCAW) process was used for welding. It involves thefusion of a flux-cored wire metal with a base metal and is awidely used semiautomatic/automatic process. 10CrNi3MoVsteel is a high-strength low-alloy steel (HSLA) widely usedin shipbuilding industry. In this work, the composition ofthe flux-cored wires was modified with varying amount ofrare-earth element (cerium rich ferro silicon). The rare-earth element modified wire was used to weld the steel. Themicrostructural, mechanical, and electrochemical propertiesof the weldment were reported highlighting the effect of therare-earth elements on the weld properties. The additionof rare-earth elements up to 0.3wt.% resulted in refiningthe second phase particles and acicular ferrite structure ofthe base metal. Further, charge-transfer channel effect ofthe second phase particles was reduced by the addition ofrare-earth elements. At the optimum composition of 0.3%

rare-earth element addition, both mechanical properties andcorrosion resistance of the weldment improved.

1.3. Research Article: “The Analysis of the Influence of VariousFactors on the Development of Stress Corrosion Defects in theMain Gas Pipeline Walls in the Conditions of the EuropeanPart of the Russian Federation”. In this research article,investigation of the stress corrosion cracking of gas pipelineshas been reported. The surveyed gas pipeline was madeof large diameter rolled steel pipes (mostly produced byKhartsyzsk Pipe Plant, KhPP). In this paper, the influencingfactors of stress corrosion defect formation and growth arereported, which were detected during the inspection andoverhaul of the main gas pipeline section. Mechanical testsby cyclic loading of samples containing cracks (field testing)showed no crack growth in the absence of corrosive medium.Mechanism of development of SCC crack was proposed.It is reported that there was a consistent pattern betweenthe width of the opening and the length of the crack. Theappearance of cracks was found to be influenced by variousfactors during different stages of life cycle, such as (i) presenceof harmful impurities that contaminate the metal pipe and(ii) presence of residual stresses in the pipe wall duringmanufacturing.

1.4. Research Article: “Pitting Corrosion of the ResistanceWelding Joints of Stainless Steel Ventilation Grille Operated inSwimming Pool Environment”. The pitting corrosion resis-tance of a stainless steel ventilation grill welded joint in aswimming pool environment is reported in this article. Inswimming pools, in addition to plastics, stainless steel is usedfor structures/equipment such as ladders, ventilation systems,barriers, and drainage grills. Ventilation grills are usuallywelded using resistance welding. Corrosion behaviour of thewelded joint showed pitting corrosion.The heat affected zonein the weldment showed severity of corrosion when com-pared to that of the base metal. The poor corrosion resistanceof the weldment was attributed to the low quality finish of theweldment, which resulted in unstable weld microstructurethat resulted in acceleration of pitting corrosion due to easeof migration of chloride ions.

2. Corrosion of Solders

2.1. Research Article: “Corrosion and Leaching Behaviours ofSn-0.7Cu-0.05Ni Lead-Free Solder in 3.5 wt.%NaCl Solution”.In this research article, a new lead-free solder alloy withcomposition Sn-0.7Cu-0.05Ni was investigated for its cor-rosion and leaching behaviour in 3.5wt.% NaCl solution.The highest corrosion rate was observed in the alloy whencompared to Sn-Cu and Sn-Ag-Cu alloys, from potentio-dynamic polarization measurements. In contrast, 30-dayleaching measurements showed reduction in leaching rate inthe developed Sn-Cu-Ni alloy solder joint when compared tothat of the Sn-Cu and Sn-Ag-Cu joints. This was attributed tothe formation of thin passivation film after 15 days. The jointshowed higher leaching rate when compared to the alloy dueto galvanic corrosion at the surface, which was confirmed bythe presence of tin oxides on the surface.

International Journal of Corrosion 3

3. Nanocrystalline Ni-Surface Coatings

3.1. Research Article: “Improvement of Corrosion Behavior ofNanostructured Ni Coating by Jet Electrodeposition and LaserRemelting”. In this research article, an effective method toimprove the corrosion resistance of Ni coating predepositedon 304 stainless steel (1Cr18Ni9) by jet electrodepositionhas been reported. The Ni coating was treated by laserremelting so as to improve the coating microstructure andinterfacial properties. Corrosion experiments revealed thatthe as-coated Ni surface had optimal corrosion resistance dueto fine grains and dense microstructure when compared tothe uncoated substrate. After laser remelting, the corrosionrate decreased significantly owing to the modification inmicrostructure and enhanced bonding between the coatingand substrate. It was identified that the corrosion behaviourof Ni coating on steel substrate can be greatly enhanced byemploying laser remelting of the coating.

Xizhang ChenArvind Singh

Sergey KonovalovJuergen R. Hirsch

Kai Wang

References

[1] G. Pimenta and T. A. Jarman, “The corrosion of metal joints,chapter 3⋅35, corrosion and degradation of engineering mate-rials,” in Shreir’s Handbook of Corrosion, pp. 2447–2462, 3rdedition, 2010.

[2] A. C. Murariu and N. Plesu, “Investigations on corrosionbehaviour of welded joint in ASTM A355P5 alloy steel pipe,”International Journal of Electrochemical Science, vol. 10, no. 12,pp. 10832–10846, 2015.

[3] C. T. Kwok, S. L. Fong, F. T. Cheng, and H. C. Man, “Pittingand galvanic corrosion behavior of laser-welded stainless steels,”Journal of Materials Processing Technology, vol. 176, no. 1–3, pp.168–178, 2006.

[4] T. P. Vianco, “Corrosion Issues in Solder Joint Design andService,” Sandia National Laboratories, Report, 1999.

[5] R. N. Parkins, Uhlig’s Corrosion Handbook, chapter 14, John-Wiley & Sons, New Jersey, NJ, USA, 3rd edition, 2011.

[6] L. Wang, J. Zhang, Y. Gao, Q. Xue, L. Hu, and T. Xu, “Grain sizeeffect in corrosion behavior of electrodeposited nanocrystallineNi coatings in alkaline solution,” Scripta Materialia, vol. 55, no.7, pp. 657–660, 2006.

[7] R. Rofagha, R. Langer, A.M. El-Sherik, U. Erb, G. Palumbo, andK. T. Aust, “The corrosion behaviour of nanocrystalline nickel,”Scripta Materialia, vol. 25, no. 12, pp. 2867–2872, 1991.

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